About Phosphorus in the Boise River? Alexandra Etheridge April 6, - PowerPoint PPT Presentation

What Does USGS Research Tell Us About Phosphorus in the Boise River? Alexandra Etheridge April 6, 2012

Preview  Boise River history and watershed characteristics  Why Phosphorus?  Spatial Phosphorus Loading 1996-2005  Flow-weighted Phosphorus trends 1994-2010  Boise River & Snake River-Hells Canyon TMDL

History of the Boise River Boise River ~1900  Late 1800s – early 1900s diversions for irrigation, mining  Dams – 1915 Arrowrock, 1950 Anderson Ranch, 1957 Lucky Peak, 1957 Hells Canyon Dam  Geomorphological changes  Water-quality changes, increased nutrients, sediment, bacteria – urban and agriculture Boise River Today  Population in Treasure Valley increased 60% from 1990 to 2010

Lucky Peak Lake

Photo by ISDA

Why Phosphorus? • Snake River-Hells Canyon TMDL – Phosphorus target = 0.07 mg/L – Excess nutrients excess algae hypoxia/death • Dissolved Phosphorus is a clear driver of Snake River algae growth • No clear relationship between nutrients and floating algae in Boise • Most algae in Boise River is benthic (attached to surfaces, bottom)

Total Phosphorous Concentrations (1996-2005) Downstream Target at Mouth 0.07 mg/L

Flow-weighted Phosphorus at Parma 1994 - 2002 Smoothed line, Irrigation Season Smoothed line, non-irrigation Season Flow-weighted = Total annual phosphorus load ÷ Total annual Q Target at Mouth 0.07 mg/L

Flow-Weighted Total Phosphorus At Parma 2003 - 2010 700 0.45 Flow-weighted annual total phosphorus concentration in USGS DATA - PROVISIONAL SUBJECT TO PEER REVIEW 0.4 589 600 Total Annual Phosphorus Load in tons 0.40 0.40 0.38 0.35 500 0.34 0.32 0.3 milligrams per liter 0.30 0.29 400 0.25 0.24 328 326 303 302 298 294 0.2 300 268 0.15 200 0.1 Target at Mouth 0.07 mg/L 100 0.05 Target at Mouth 97 ton/yr (based on 242 kg/d) 0 0 2003 2004 2005 2006 2007 2008 2009 2010

Robust Data 2008-2010 Study: What does Boise What we found: Contribute to Snake?  Boise River contributes 30% of TP  Funded by municipalities and USGS and 72% of OP in Snake  TP at Parma every 49 h  Boise River has higher TP in winter  Weekly sampling during Irrigation season in Snake and Boise  Boise River more dissolved than particulate  Estimated daily loads  Snake River more particulate than  15-minute water-quality parameters dissolved  Surrogates  Phosphorus drives algae growth in Snake

Snake River Phosphorus & Floating Chlorophyll-a (Algae) Overall spearman’s rho = -.64

Relative Contribution to Snake Boise River contributes 11% of mean annual flow in Snake Total Phosphorus Orthophosphorus Boise -11% Snake 17% 30% Other 39% 72% 53% Total Nitrogen Chlorophyll-a 2% Suspended Sediment 8% 12% 13% 15% 37% 50% 77% 86% Net uptake of OP in Snake River, Owyhee River contributes ~2 – 4 % of nutrient loads measured at Nyssa

Total Phosphorus 2008 - 2010  All measured TP concentrations in Boise River exceeded the seasonal target of 0.07 mg/L  At Adrian - 13% exceeded target  At Nyssa – 64% exceeded target

Summary  Most phosphorus in the Boise river is dissolved  Phosphorus increases downstream  Dissolved phosphorus delivered by the Boise River floating algae growth in the Snake River

Questions

USGS & IDEQ Synoptic Study  3 Synoptic sampling events  August 2012  October 2012  February 2013  Up to 40 sites  25-30 surface water  10-15 groundwater  Phosphorus mass balance model  USGS Open File Report by June 30, 2013

Phosphorus Data Summary 1994 -2005 Explanation Total Number of Samples 55 Upper Adjacent (Largest result between 75 th & 100 th percentile) 75 th percentile (75% of results are lower than this) Median 25 th percentile (75% of results are higher than this) Lower Adjacent (Lowest result between 25 th & 0 percentile) Outlier

Total Phosphorus Surrogate Model Boise River Seasonal Average TMDL Target

GW source of phosphorous to lower Boise River 1.2 Caldwell Near 1.1 Mason Slough Dissolved Phosphorous, in mg/L 1.0 Right Bank Notus Center of River 0.9 Left Bank Parma 0.8 Middleton Surface Water 0.7 Eagle Island 0.6 0.5 0.4 Glenwood 0.3 Bridge Diversion 0.2 Dam 0.1 0.0 0 10 20 30 40 50 60 70 River Mile

Estimated Mean Monthly Total Phosphorus Loads in pounds per day Boise River Near Parma, Idaho WY2003 - WY2008 Mean Monthly Total Phosphorus Loads - lbs/day Estimated TP Load 7,100 10000 95% Confidence Interval Daily Mean Flow Daily Mean Flow in cubic feet per second 6,100 1000 5,100 4,100 100 3,100 2,100 10 1,100 USGS DATA - PROVISIONAL SUBJECT TO PEER REVIEW 100 1

Estimated Mean Monthly Total Phosphorus Loads Boise River Near Parma, Idaho WY2003 - WY2008 7,000 USGS DATA - PROVISIONAL SUBJECT TO PEER REVIEW 6,000 Mean Monthly Total Phosphorus Loads in pounds per day 5,000 2003 4,000 2004 2005 2006 3,000 2007 Most recent biological sampling 2008 2,000 1,000 0

Sediment Concentrations (1996-2005)